Swirl injector for internal combustion engine

ABSTRACT

The swirl injector for an internal combustion engine is an electronic fuel injector for a direct injection engine, either gasoline or diesel. The injector has a housing defining a fluid channel, a needle valve disposed in the fluid channel with a spring biasing the valve to a closed position, and a solenoid disposed in the housing encircling the fluid channel. The injector has a nozzle with a conical valve seat and a cylindrical discharge orifice. The needle tip is ball shaped, and the needle body has a plurality of helical grooves which are rectangular in cross section having a width to depth ratio of 1.5:1 at about a 46° angle adjacent the tip. The valve lift is 50 μm in 60 μs. The penetration, swirl speed, and pitch angle are controllable through the injection pressure, providing an enhanced fuel injector for dual mode fuel injection.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a divisional application of U.S. Ser. No. 09/854,621,filed May 15, 2001, which is a continuation-in-part of Ser. No.09/614,381, filed Jul. 3, 2000.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a swirl injector for an internalcombustion engine, and particularly to a fuel injector for a directinjection engine, which may be either a spark injection gasoline engineor a compression ignition diesel engine, which imparts a swirling motionto the fuel during injection to improve injection characteristics andperformance The swirl injector has novel characteristics which enableadjustment of the injector's spray pattern to the phase of the strokecycle, and may be used with a novel on-board flow meter which providesfeedback to the engine control unit for adjusting injectioncharacteristics.

[0004] 2. Description of the Related Art

[0005] In recent years there has been a renewed interest in directinjection gasoline engines due to the greater fuel economy that can beachieved with direct injection engines, both for the sake of the savingsin fuel costs and for the reduction in greenhouse gases consequent onreduced hydrocarbon fuel usage. The majority of gasoline fuel injectionengines still use either throttle body injection or port injection intothe intake manifold. Efforts towards using direct injection in gasolineengines have been complicated by the difficulty in finding a fuelinjector which is capable of producing a homogenous air-fuel mixtureduring early fuel injection for a full load and a stratified air-fuelmixture during late fuel injection for a partial load, by controlling astratified air-fuel mixture over a wide range of operating loads, and bythe need for a rapid and smooth switching system for switching betweenearly and late fuel injection. See SAE Technical Paper 970540,“Development of Direct Injection Gasoline Engine”, Harada et al.,February, 1997, and SAE Technical Paper 970541, “Development of GasolineDirect Injection Engine”, Iwamoto et al., February, 1997.

[0006] On the other hand, diesel engines may use direct injection intothe combustion chamber, injection into a precombustion chamber connectedto the main combustion chamber, or injection into a swirl chamberconnected to the main combustion chamber. Direct injection is used withmost heavy duty, high-speed diesel engines due to its greater fueleconomy. A precombustion chamber is used with most passenger vehiclesbecause of the smoother combustion and lower noise level available, atthe cost of decreased fuel economy. A swirl chamber increases fueleconomy over a precombustion chamber, but requires more precisemachining, engineering, and matching of components. Fuel injectors fordiesel engines were largely mechanically actuated and controlled untilthe 1980's. With the advent of concerns about emission controls and thedevelopment of automotive electronics, diesel engines now use electroniccontrol modules or units to control the metering and timing of fueldelivery, although actuation of the injector plunger may still be donemechanically to develop the high injection pressures needed. Arepresentative example is the fuel injector used in the Detroit DieselSeries 60 engine, described in Diesel Technology, Norman et al., pp.510-512 (Goodhart-Willcox Company, Inc., 2001), in which a cam activatedrocker arm depresses the injector plunger, raising the fuel pressure tounseat the needle valve, while fuel metering is controlled by a solenoidactivated poppet valve. Smaller direct injection diesel engines may relyentirely on air swirl for mixing air and fuel in the combustion chamber,although some mechanical injectors for diesel engines provide forswirling the fuel as it leaves the injector.

[0007] Various solutions have been proposed to address these problems.U.S. Pat. No. Re. 34,527, issued Feb. 1, 1994 to Yoshida et al.describes a fuel injector having helical grooves. The patent isparticularly directed to the feeder wire structure for theelectromagnetic structure. U.S. Pat. No. Re. 34,591, issued Apr. 26,1994 to Yoshida et al., shows the same injector as the '527 patent, butis directed to the submagnetic structure which controls the amount oflift.

[0008] U.S. Pat. No. 4,192,466, issued Mar. 11, 1980 to Tanasawa et al.,shows a swirl injector for a diesel engine having a swirl chamber. U.S.Pat. No. 4,230,273, issued Oct. 28, 1980 to Claxton et al., describes aninjector switchable between single point and multi-point injectionsystems. The embodiment shown in FIG. 9 has helical grooves, but appearsto be a pintle type not designed for dual injection. U.S. Pat. No.4,365,746, issued Dec. 28, 1982 to Tanasawa et al. teaches a swirlinjector having helical grooves which only extend through a radial angleof 60-100° around the needle body.

[0009] U.S. Pat. No. 4,629,127, issued Dec. 16, 1986 to Kawamura et al.,teaches a fuel injector having grooves in the needle and adjusting thespray angle by adjusting the area of the gap between the valve needleand valve wall, the area of the grooves, and the angle of the grooves.U.S. Pat. No. 4,653,694, issued Mar. 31, 1987 to Noguchi et al.,discloses a fuel injector in which the spray angle is adjusted bytapering the walls of the valve body and the needle, and by adjustingthe lift height to vary with the load.

[0010] U.S. Pat. No. 4,721,253, issued Jan. 26, 1988 to Noguchi et al.,describes a swirl injector which uses a straight passage between theneedle and the valve body combined with a tangential groove to provide aspray with both angle and straight components. U.S. Pat. Nos. 4,974,565and 5,058,549, issued Dec. 4, 1990 and Oct. 22, 1991, respectively, toHashimoto et al., teaches a fuel injector with either tangential groovesor projections to impart swirl to the fuel spray, but uses two orificesin the nozzle to provide both wide and narrow spray angles.

[0011] U.S. Pat. No. 5,163,621, issued Nov. 17, 1992 to Kato et al.,shows a fuel injector with multiple orifices in the nozzle arranged atdifferent angles, and a needle valve tip having conical sections ofdifferent diameters, the injection angle and velocity being adjusted byvarying the amount of lift. U.S. Pat. No. 5,163,621, issued Jul. 28,1998 to Furuya et al., describes a swirl fuel injector having a conicalneedle tip with different diameter conical sections to adjust the sprayangle by the gap between the tip and the valve seat.

[0012] U.S. Pat. No. 5,983,854, issued Nov. 16, 1999 to Machida et al.,teaches a switching scheme for switching between uniform fuel mixturecombustion injection on the intake stroke and stratified combustion onthe compression stroke by a CPU and gate circuits which test what theload condition is. Japanese Patent No. 1,227,865, published Sep. 12,1989 shows a fuel injector with a pilot nozzle and a main nozzle havingmultiple orifices, and a controller which times injections to overlapsprays from the pilot and main nozzles. Japanese Patent No. 3,033,422,published Feb. 13, 1991, teaches stratified combustion obtained bypositioning of the spark plug relative to the spray pattern.

[0013] Japanese Patent No. 10,311,264, published Nov. 24, 1998;discloses an injector with helical grooves in the needle and acylindrical element between the helical grooves and the conical tipwhich is termed a fuel regulator. Japanese Patent No. 11,082,229,published Mar. 26, 1999, shows a fuel injector similar to the Japanese'264 patent, but with a countersunk groove in the base of, the injectorbody to collect any fuel spit-back after injection.

[0014] Applicant is aware of a fuel injector designed by Applicant forUnisia Jecs Co. in 1997-98 and installed in Nissan Motor Company 2.2Lengines beginning with April, 1998 with some common structuralsimilarities to the fuel injector of the present invention. The basicconstruction and operational differences between the injector developedfor Unisia Jecs and the fuel injector of the present invention are asfollows:

[0015] 1. The contact zone between the needle and the valve seat hasbeen redesigned. The new design and sizing of the needle ball head,conical nozzle and outlet cylindrical part of the nozzle suppressesshock vibrations of the needle after valve closing to prevent postinjection of fuel into the cylinder head and to remove particulateemissions observed in the Unisia Jecs injector.

[0016] 2. The needle swirling channels have been redesigned. The angleof the channels has been changed from 37° to 46°. The Unisia Jecsinjector has concave channels. The present fuel injector has arectangular profile or cross-section, with the ratio of width-to-depthof 1.5. These changes permit a 2.3 increase of swirling (rotational:speed and simultaneously damped pulsation at 50% of the umbrella part ofthe spray structure, resulting in higher spray quality, i.e., the timeneeded to get a micro-spray is decreased to 350 μs from 800 μs.

[0017] 3. In the Unisia Jecs injector the lifting gap was 70 μm and theresponse time was limited by the solenoid capacity to 120 μs. In thepresent fuel injector the lifting gap is 50 μm and the response time is60 μs, resulting in a higher jet penetration speed and the swirlingspeed of the umbrella fraction of the spray.

[0018] 4. In the Unisia Jecs injector, two voltage levels (−7/+12V and−5/+24V) were used to operate the injector in dual switch mode withpartial and full load, respectively. With the present fuel injector, thesolenoid wiring has been redesigned to provide a continuous change ofthe lifting force at the same voltage input of 24 or 42 volts directlyfrom the engine power supply. The current supplied to the solenoidcontrols the continuous operation of the fuel load.

[0019] Some of the properties of the Unisia Jecs injector were measuredand described by the Applicant in Ismailov et al., “LDA/PDA measurementsof instantaneous characteristics in high pressure fuel injection andswirl spray”, Experiments in Fluids, Vol. 27, pp. 1-11 (1999).

[0020] Transducers or sensors permanently mounted on engines formeasuring injection characteristics have generally been limited toelectromagnetic devices which measure pressure or volume, rather thanoptical devices, such as those described in U.S. Pat. No. 3,937,087,issued Feb. 10, 1976 to W. S. Heggie (coil wrapped around fuel pipelinewhich presents variable resistance for sensing tube expansion); U.S.Pat. No. 4,073,186, issued Feb. 14, 1978 to C. L. Erwin, Jr.(electromagnetic sensor); and U.S. Pat. No. 4,192,179, issued Mar. 11,1980 to E. Yelke (piezoelectric sensor).

[0021] Optical devices for measuring fuel flow in injection systems areshown in two Japanese patents. Japanese Patent No. 8-121,288, publishedMay 14, 1996, shows a device for measuring injection rate with apressure sensor for measuring the force of injection and a laser Doppleranemometer for measuring velocity, and which uses a mathematical formulawhich relates force and velocity to flow rate. Japanese Patent No.8-121,289, published May 14, 1996, describes a device which uses twolaser Doppler anemometers, one in the main supply line, the other in abias flow generating unit fed by a divider pipe, to measure the flowrate by a differential flow rate method. Neither of these devices showan on-board sensor with a laser diode source and PIN diode detector.

[0022] None of the above inventions and patents, taken either singularlyor in combination, is seen to describe the instant invention as claimed.Thus a swirl injector for an internal combustion engine solving theaforementioned problems is desired.

SUMMARY OF THE INVENTION

[0023] The swirl injector for an internal combustion engine is anelectronic fuel injector for a direct injection engine, either gasolineor diesel. The injector has a housing defining a fluid channel, a needlevalve disposed in the fluid channel with a spring biasing the valve to aclosed position, and a solenoid disposed in the housing encircling thefluid channel. The injector has a nozzle with a conical valve seat and acylindrical discharge orifice. The needle tip is ball shaped, and theneedle body has a plurality of helical grooves which are rectangular incross section having a width to depth ratio of 1.5:1 at about a 46°angle adjacent the tip. The valve lift is 50 μm in 60 μs. Thepenetration, swirl speed, and pitch angle are controllable through theinjection pressure, providing an enhanced fuel injector for dual modefuel injection.

[0024] In particular, by applying a lower injection pressure (about 5.0MPa for gasoline engines and 60.0 MPa for diesel engines), the injectorprovides a pitch angle (measured from the injector's longitudinal axisto the axis of the fuel's core jet) close to 3°, with lower penetrationand swirl speeds, which provides lean fuel consumption for lateinjection (during the compression stroke) for a partial load, such asconstant speed cruising. On the other hand, by applying a higherinjection pressure (about 7.0 MPa for gasoline engines and 90.0 MPa fordiesel engines), the injector provides a pitch angle close to 150, withhigher penetration and swirl speeds, which serves to concentrate thecore jet on a controllable point of the piston's surface in anultra-short time span less than 100 is for more power for earlyinjection (during the intake stroke) for a full load, such asacceleration from a stop or climbing a hill.

[0025] The performance and rapid response capabilities of the injectormay be improved, particularly with diesel engines, by using the swirlinjector in combination with a flow meter capable of measuringinstantaneous volumetric flow rates or pressure gradients in the fuelpipeline.

[0026] Accordingly, it is a principal object of the invention to providea swirl injector which provides electronic fuel injection for use ineither a direct injection spark ignition (gasoline engine), or a directinjection compression ignition (diesel) engine.

[0027] It is another object of the invention to provide a swirl injectorwith controllable pitch angle, penetration speed, and swirl speed foruse as a dual mode fuel injector capable of early injection (during theintake stroke) when under full load and late injection (during thecompression stroke) when under partial load.

[0028] It is a further object of the invention to provide a swirlinjector having a needle valve with a ball tip and helical grooves onthe needle body adjacent the needle tip having an angle and crosssectional area adjusted to provide a fuel spray having a core jet andspray umbrella of appropriate velocity and penetration for early or latefuel injection, depending on the triggering characteristics.

[0029] Still another object of the invention is to provide a swirlinjector having the needle valve lift distance and speed optimized toprovide ultra-short injection speed.

[0030] It is an object of the invention to provide improved elements andarrangements thereof for the purposes described which is inexpensive,dependable and fully effective in accomplishing its intended purposes.

[0031] These and other objects of the present invention will becomereadily apparent upon further review of the following specification anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is a diagram showing a typical spray pattern from a swirlinjector.

[0033]FIG. 2 is a fragmented diagram showing a three dimensional swirlpattern having vertical and horizontal components.

[0034]FIGS. 3A and 3B are prior art charts showing the axial sprayvelocity as a function of time for direct injection gasoline engines atlow and high injection pressures, respectively.

[0035]FIGS. 3C and 3D are prior art charts showing the radial sprayvelocity as a function of time for direct injection gasoline engineswith a swirl injector at low and high injection pressures, respectively.

[0036]FIGS. 4A, 4B and 4C are prior art charts showing the instantaneousaxial velocity, mean Sauter diameter, and droplet concentration,respectively, in a swirl injector spray versus radial position atdifferent axial cross sections at a 90° injection phase.

[0037]FIG. 5 is a cross section of a swirl injector for internalcombustion engines according to the present invention.

[0038]FIG. 6 is a detail section view showing the ball tip of the needlevalve and the valve seat in a swirl injector according to the presentinvention.

[0039]FIG. 7 is a block diagram showing a flow meter sensor in-line witha swirl injector according to the present invention.

[0040]FIG. 8 is a section view of an on-board flow meter for use incombination with the swirl injector of the present invention.

[0041] Similar reference characters denote corresponding featuresconsistently throughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] The present invention is a swirl injector for an internalcombustion engine. More particularly, the swirl injector is anelectronic fuel injector for a direct injection engine, which may beeither a spark ignition (SI) gasoline engine, or a compression ignition(CI) diesel engine. The swirl injector is designed for use in a dualmode fuel injection system, in which injection may occur during theintake stroke (early injection) while the engine is operating under fullload, such as during acceleration from a full stop or climbing a hill,or during the compression stroke (late injection) while the engine isoperating under a partial load, such as cruising at constant speed.

[0043] The spray pattern produced by a swirl injector is shown inFIG. 1. A swirl injector A is supplied by a high pressure fuel line Band emits a spray through a nozzle C. The spray includes a core jet D ofdroplets concentrated in a narrow diameter jet defining an axialpenetration front J and a quasi-umbrella shaped fan Q of more widelydispersed droplets defining a radial penetration front U. A transitionzone T proximate the nozzle C marks an area where atomized dropletsdisperse from the core jet D into the quasi-umbrella shaped fan Q. Asshown by the arrows in FIG. 2, the quasi-umbrella shaped fan Q describesa three-dimensional swirling pattern resulting from a vertical velocitycomponent urging the spray in an axial direction and a horizontalcomponent urging the spray in a radial direction.

[0044]FIGS. 3A and 3B show test data for a Unisia Jecs Co. swirlinjector, charting the axial velocity, U_(a) versus the penetration timefor injector pulse widths of 0.25 ms, 1.00 ms, and 4.00 ms at injectionpressures of 5 MPa and 7 MPa, respectively. FIGS. 3C and 3D show theradial velocity, U_(r), versus penetration time for injector pulsewidths of 1.00 ms and 4.00 ms at injection pressures of 5 MPa and 7 MPa,respectively. In the charts, the zones (i), (ii) and (iii) correspond toperiods of fluid jet propagation, transformation of the jet into dropletspray, and swirling spray motion, respectively.

[0045]FIGS. 4A, 4B and 4C show the instantaneous axial velocity, U_(ax),mean Sauter diameter, D₃₂, and the normalized particle number,N_(part)/N_(part), versus radial position through spray cross-sectionsat five different axial distances from the nozzle for the same UnisiaJecs swirl injector.

[0046] As shown by the data in the above Figures, it is possible tocontrol the spray penetration speed and spatial dynamic distribution interms of timing and cylinder space, and to obtain a very high quality ofthe fuel spray, as shown by the Sauter mean diameter, within anultra-short, controllable injection span of 0.25 to 8.0 ms. The swirlinjector of the present invention is designed to avoid certain problemsassociated with the Unisia Jecs swirl injector, including: particulateemission from post-injection fuel in the cylinder head; improved swirlvelocity from redesign of the nozzle for more rapid micro-sprayformation; improved lift gap and speed for higher jet penetration andswirling speed; and improved solenoid control voltage for continuousoperation of the fuel load.

[0047] The swirl injector of the present invention, designated generallyas 10 in the drawings, is shown in FIGS. 5 and 6. The injector 10 has ahousing 12 defining a fluid channel 14, a needle valve 50 disposed inthe fluid channel 14 biasing the valve to a closed position, and asolenoid 80 disposed in the housing 12 encircling the fluid channel 14.The housing 12 includes several components assembled to form anelongated and generally cylindrical valve body. The housing 12 has ahigh pressure inlet plug 16 adapted for connection to an enginehigh-pressure fuel line using a plug-in inlet part of the injector witha cylinder-ball convex, fixing hole at the plug head. The diameter,height and wall thickness of the inlet plug 16 may be varied for anyconfiguration of gasoline or diesel engine. The inlet plug 16 has a boredefined therein with a fuel filter 18 disposed in the upper part of thebore.

[0048] The housing 12 has a ground housing 20 encircling the middleportion of the inlet plug 16 and an installation housing 22 abutting ashoulder on the ground housing 20 and enclosing the lower portion of theground housing 20. Elastic O-ring 46 maintains the installation housing22 snugly mounted on the ground housing 20. A conical head nozzle 24 hasan upper portion enclosed by the ground housing 20 and a lower portionextending through a bore in the installation housing 22. Elastic O-ring48 maintains the nozzle 24 snugly mounted in the ground housing 20. Theinstallation housing 22 is adapted for connecting the injector 10 to thefuel injection port in the cylinder head and prevents the nozzle 24 fromcontacting the metal surface of the cylinder.

[0049] The solenoid 80 includes a coil 26 wound on a ground ring housing28 and covered by a polar ring housing 30. The solenoid 80 encircles thelower portion of the inlet plug 16 and the assembly is held together byelastic O-rings 32 and 34. A polar electrode 36 is electricallyconnected to the coil 26 and extends through the ground housing 20 forattachment to wiring from a triggering circuit for controlling thetiming and pulse duration of the injector 10. The coil 26 is made fromwire having a diameter and number of turns capable of handling currentproduced by full battery voltage, either 24V or 42V, to continuouslyvary the current to achieve a quick lift time without burning out thecoil 26. The battery may be connected to the solenoid 80 by a relayswitched by a voltage controlled by the engine control unit.

[0050] The housing 12 includes a blocking plug 38 disposed in the boredefined in the inlet plug 16 and a helical compression spring 40disposed below the blocking plug 38. A nozzle head housing 42 abuts thelower end of the inlet plug 16 and is encircled by the lower end of theground ring housing 28 and the ground housing 20. The nozzle headhousing 42 defines a continuation of the fluid channel 14. A shock brakering 44 is disposed between the nozzle head housing and the nozzle 24.

[0051] A needle valve 50 is disposed in the fluid channel 14 defined bythe housing 12. The needle valve has a lower portion disposed in thenozzle 24 and a head 52 disposed in the needle head housing 42 andextending at least partly inside the solenoid 80, the upper end of theneedle valve 50 compressing spring 40. An annular stop disk 54 isdisposed about the needle valve 50 below the shock brake ring 44. Asmall lifting gap 56 of about 50 μm separates the disk 54 from the shockbrake ring 44 when the needle valve 50 is biased in the closed position,permitting fuel to flow past the nozzle head 52 and through the shockbrake ring 44 to fill a small reservoir 58 surrounding the disk 54 andaround the lower end of the needle 50 up to the tip of the needle 50.

[0052]FIG. 6 shows a detail view of the tip of the needle valve 50 andthe conical head nozzle 24. The nozzle 24 defines a conical valve seat60 with a cylindrical discharge orifice 62 descending; from the apex ofthe cone to the bottom surface of the nozzle 24. The needle 50 has aball shaped tip 64 which generally defines a circular section in theconical valve seat 60 when the injector valve is in the closed position.The lower portion of the needle 50 has a plurality of helical ridges 66wound around its circumference which define a plurality of helical orspiral grooves 68. The spiral grooves 68 do not have a round or arcuatebottom; rather, the ridges 66 define grooves 68 which have a planarbottom wall and planar side walls. The grooves 68 preferably have awidth-to-depth ratio of about 1.5:1. The grooves 68 preferably define anangle θ of 46° with respect to an axis extending transverse to thelongitudinal axis of the needle 50. The ridges 66 closely abut thecylindrical bore defined in the nozzle 24 above the conical valve seat60 so that fuel is forced to flow through the spiral grooves 68 to reachthe discharge orifice 62. A preferred diameter of the cylindricaldischarge orifice 62, indicated by the dimension line 70, is about 0.8mm. A preferred, mean diameter of the circular section defined bycontact of the ball tip 64 with the conical valve seat 24, indicated bythe dimension line 72, is about 1.5 mm. A preferred diameter of thecylindrical bore defined in the nozzle 24 above the conical valve seatis about 4.0 mm.

[0053] In use, the needle valve 50 oscillates between an open positionand a closed position under control of the solenoid 80 and thecompression spring 40. When the solenoid 80 is energized, the needlevalve 50 is attracted by the magnetic field of the coil 26, liftinguntil the disk 54 is stopped by the shock brake ring 44 and compressingspring 40. This action lifts the ball tip 64 off the valve seat 60,permitting fuel to flow directly into the combustion chamber. Whencurrent to the solenoid 80 switches off, the resilient force of thecompression spring 40 moves the needle valve 50 downward, seating theball tip 64 on the valve seat 60 to shut off the flow of fuel into thecombustion chamber defined in the cylinder. Advantageously, the ball tip64 provides a tight seal with the valve seat 60 and preventspost-injection fuel leakage into the cylinder that occurs with conicalneedle tips and which may cause soot in the exhaust emissions andparticulate build-up in the discharge orifice, adversely affecting thespray pattern.

[0054] The lifting gap section defined by the shock brake ring 44 andthe stop disk 54 subdivides the flow into two volumes, a flow upstreamfrom the lifting gap 56 (Volume-1), and a fuel volume downstream fromthe lifting gap 56 (Volume-2).

[0055] The needle's 50 mass is preferably about 5 grams, and movesupstream under the influence of the magnetic field of the solenoid undera force ΔF=2 kg-f (20N) with approximately constant acceleration a=4·10³m/s. The value ΔF is the difference in the forces produced by thesolenoid 80 and the compression spring 40. The lifting gap is about 50μm and the lifting time is about 60 μs, which is much less than anyother operational characteristic time, such as the viscous constant,injection time, etc. The ultra short, needle lifting time cannot affectany additional disturbances into the transient flow into the injectorother than those produced under the forced pressure gradient, theinjector configuration (boundary conditions) and injection timingdynamics (initial conditions).

[0056] A fuel, pressurized by a fuel pump at 5.0 to 7.0 MPa for gasolinedirect injection engines or 60.0 to 100.0 MPa for diesel directinjection engines, flows through a high pressure fuel pipeline into theinlet plug 16, flows through the bore in the blocking plug 38 and thecompression spring 40, around the needle valve head 34, and settles intoa chamber 74 defined by the needle head housing 42 and the shock brakering 44 when the needle valve 50 is raised to an open position. At thesame time, a portion of fuel about 1.2 mm³ deposited in Volume-2 isflowing out from the nozzle 24 due to the open space between the balltip 64 and the valve seat 60. Due to the pressure differential of thehigh pressure in the injector 10 and the ambient pressure in thecombustion chamber, the fuel flow initially accelerates straightdownstream (an axial momentum transferred afterwards to the core jet D)in the cylindrical discharge orifice 62. Thereafter the flow is shapedby passage through the spiral grooves 68 in a screwing action thatimparts a 3-dimensional swirling momentum to the flow, shown in FIG. 2.

[0057] Proper selection of the axial screwing period (length), thenumber of grooves 68, and the cross-sectional area of the grooves isdependent on the engine type. For example, in a gasoline engineinjecting under a pressure of 7.0 MPa, the screwing period is 7.98 mm,the number of grooves is six, and the cross-sectional area of thegrooves 68 is 0.23 mm². Under these conditions a very precise amount offuel may be injected at a rate up to 15.0 mm³/ms. For a diesel engineinjecting under a pressure of 80.0 MPa, the screwing period is 5.67 mm,the number of grooves 68 is eight, and the cross-sectional area of thegrooves 68 is 0.34 mm². Under these conditions, a very precise amount offuel may be injected at a rate up to 35.0 mm³/ms.

[0058] The flow goes to the nozzle 24 cut edge, oscillates, and breaksup into ligaments to droplets. However, due to the two differentmomentums, axial and swirling, from an early stage the ejected fuelspray develops as the superimposed structure of the umbrella-like sprayQ and the core jet D, as shown in FIG. 1. Due to the high swirling speedgenerated (up to two thousand revolutions per second) and the Coriolisforce resulting from rotation, the spray angle can be targeted on apitch angle from 3° to 15° measured from the injector axial axis to theaxis of the core jet.

[0059] This spray flow-refocusing feature of the injector 10 becomesvery important to adapt the injector 10 for both injection modes, earlyand late. For a given injector configuration, the swirl speed isdependent only on the injection pressure, which is a controllable andvariable value. In an early injection mode (during the intake stroke)there is a large spread space-in the combustion chamber defined in thecylinder and a relatively long time to form a fine fuel spray. Applyinga lower injection pressure (5.0 MPa for a gasoline engine and 60.0 MPafor a diesel engine) the injector 10 will eject fuel at a pitch angleclose to 3°, providing low penetration and swirl speeds. For lateinjection (during the compression stroke) there is a small spread spacein the combustion chamber defined in the cylinder and a relatively shorttime to form a fine fuel spray. A higher injection pressure (maximalpressure level, 70 MPa for a gasoline engine and 90.0 MPa for a dieselengine) applied to the injector 10 will eject fuel at a pitch angleclose to 15°, providing higher penetration and swirl speeds than inearly injection mode. This permits adjusting injector operation to anyengine cylinder with different piston sizes and shapes and controllingthe amount of fuel injecting in either early or late injection mode.

[0060] When the solenoid 80 is de-energized, the needle valve 50 isforced downward by expansion of the compression spring 40 under a forceF=15N in a period of 0.18 ms, seating the ball valve 64 on the valveseat 60 to block further injection. With this downward movement, thestop disk 54 is detached from the shock brake ring 44 and opens thelifting gap 56 to 50 μm, allowing a metered quantity of fuel to comeinto Volume-2 from Volume-1. The injector 10 has excellent performancecharacteristics in providing a rapid response to vary the injectionperiod with engine speed in a few milliseconds, and a controllableinjection duration down to an ultra-short level of about 0.25 ms. Thispermits operation in either an early or late injection mode.

[0061] The hardware components of the injector housing 12 and the needlevalve are preferably made from stainless steel. The O-rings 32, 34, 46,and 48 require a special composition due to the extremely fast changesin pressure that deform and stretch all injector units. The elasticityof the O-rings plays an important role because the stretching volume canaffect the volume of fuel deposited in Volume-1 and Volume-2, andtherefore the properties of the ejected fuel stream. The O-rings must beable to operate in a wide range of stresses, up to 100 kg/cm² forgasoline engines and up to 400 kg/cm² for diesel engines, and the O-ringloading specific volume change should be limited to 10% of the fullunstretched O-ring volume. It was found that a material meeting theserequirements is a fabricated composition of mineral rubber withspecifically selected chemicals working as a dispersing agent, atackier, and a reinforcement agent. Hard clay may be used as thetackier, a combination of EPC black and FT black as the dispersingagent, and a combination of MgCO₃, ZnO, BaSO₄ and CaCO₃ as thereinforcing agent.

[0062] Although the swirl injector 10 provides improved performance overpresent fuel injectors using existing electronic engine controls, theperformance of the swirl injector 10 may be enhanced, particularly fordiesel engines, by using the swirl injector 10 in combination with anovel on-board flow meter sensor capable of measuring instantaneousvolumetric flow rates and pressure gradients. The flow meter sensor isdescribed more particularly in my co-pending U.S. patent applicationtitled FLOW METER, filed concurrently with the present application.

[0063] As shown in FIG. 7, the flow meter sensor 100 is connected in thefuel pipeline between the fuel pump 102 (or the fuel tank depending onthe engine configuration) and the injector 10. The flow meter 100provides signals for measuring the instantaneous center line velocity inthe fuel line to an interface board on the engine control module 104,which uses software implementing a precise solution to the Navier-Stokesequations for a periodically oscillating transient flow in a pipe toprovide instantaneous volumetric flow rates and pressure gradients tothe engine control module 104. The engine control module 104 alsoreceives input from a variety of other sensors, including, but notlimited to, a mass air flow sensor 106, an exhaust gas recirculationsensor 108, a speed sensor 110, and a throttle position sensor 112. Theengine control module 104 may be programmed to adjust the injection mode(early or late), timing, duration, and pressure in response to loadconditions and emissions standards in order to adjust the volumetricflow rate and spray pattern for maximum fuel economy, power, andemissions compliance.

[0064] As shown diagrammatically in FIG. 8, the on-board flow metersensor 100 constitutes a section of pipe which is inserted in the fuelpipeline. The flow meter 100 has a steel jacket 120 enclosing a quartzcapillary tube 122 which is open at both ends for connection to the fuelpipeline. The quartz tube 122 has an inside diameter which preferablymeasures between 2.5 and 3.5 mm. A laser Doppler anemometer is mountedon the quartz tube 122 through an, opening in the steel jacket 120. Theoptical components of the, anemometer comprise a laser diode 124 lightsource emitting a laser at 832 nm and 18 mW which is simultaneouslysplit into a number of beams (symmetrically spread as zero-, first-,second-, etc. orders), including two symmetrical first order beams whichare collimated using an optic fiber of 10 μm precisely adjusted on the,laser diode stripe normally to the main axis of the elliptical cone, amask for blocking all beams except the two first order beams and forfocusing the two first order beams to intersect in the centerline offuel flow in the quartz tube 122, and a pin diode 126 with an opticfiber collimator to receive the scattered light from the controlmeasurement zone defined by the intersection of the two beams in thecenter line of the quartz tube 122.

[0065] Current produced in the pin diode 126 is fed to an interfaceboard 128 for calculating the instantaneous center line velocity of fuelflow, and the data from the interface board 128 is fed to the enginecontrol module 104 for calculating volumetric flow rates with themodule's microprocessor. Preferably the interface board 128 is builtinto the engine control module 104. The engine control module 104 mustbe capable of 1,000 operations per second for running sensor operationand optimal combustion setup.

[0066] Operation of the swirl injector 10 with the on-board sensor 100results in an increase in fuel economy of 14-22%, power increase, andreduced exhaust emissions, especially with respect to diesel engines,due to online optimized combination of injection pressure, fuel sprayquality, and precision timing of injection and ignition.

[0067] It is to be understood that the present invention is not limitedto the embodiments described above, but encompasses any and allembodiments within the scope of the following claims.

I claim:
 1. A swirl injector for a direct injection internal combustionengine comprising: (a) an elongated housing defining a valve body andhaving a fluid passage defined axially through the valve body, thehousing having a fluid inlet plug at a first end adapted for attachmentto a pressurized fuel line, and having a nozzle defining a conical valveseat at a second end for discharging fuel, the nozzle further defining asingle cylindrical discharge orifice descending from the apex of theconical valve seat, the housing further having a shock brake ringdisposed transversely in the fluid passage and defining an upper valvebody portion and a lower valve body portion; (b) a solenoid disposed inthe upper valve body portion of said housing, the solenoid having a coilencircling the fluid passage and a polar electrode electricallyconnected to said coil, the polar electrode extending through saidhousing and being adapted for connection to a triggering circuit forenergizing the solenoid for precise time durations at precisely timedintervals; (c) a needle valve having a needle head at a first end and aball tip at a second end, the needle valve having a disk about itscircumference, the needle valve being disposed in the fluid passagedefined in said valve body with the disk disposed in the lower portionof said valve body and the needle head extending at least partiallyinside the coil of said solenoid, the needle valve having a plurality ofhelical ridges defining spiral grooves adjacent the ball tip; and (d) acompression spring disposed in the upper portion of said valve body; (e)wherein said compression spring biases the needle valve in a closedposition in which the ball tip is seated against the conical valve seatdefined in said nozzle and wherein a triggering; current in saidsolenoid lifts said needle valve to an open position in which the balltip is raised above the conical valve seat in order to discharge fuelfrom the nozzle; and (f) wherein said swirl injector ejects a fuel sprayhaving an umbrella spray superimposed on a core jet at a penetrationspeed swirl speed, and pitch angle controllable by varying injectionpressure for operation in a dual switch mode between early injection andlate injection.
 2. The swirl injector according to claim 1, wherein thespiral grooves are defined by a planar bottom wall and a pair ofopposed, planar side walls.
 3. The swirl injector according to claim 2,wherein the spiral grooves have a width-to-depth ratio of 1.5 to
 1. 4.The swirl injector according to claim 1, wherein the spiral groovesdefine an angle of about forty-six degrees with respect to an axistransverse to a longitudinal axis of said needle valve.
 5. The swirlinjector according to claim 1, wherein the stop disk of said needlevalve and said shock brake ring define a lifting gap when said needlevalve is in the closed position, the lifting gap measuring about 50 μm.6. The swirl injector according to claim 5, wherein said solenoid iscapable of developing an electromagnetic field of sufficient strength toraise said needle valve to a closed position in which said stop disk isseated against said shock brake ring in about 60 μs.
 7. The swirlinjector according to claim 1, wherein the coil of said solenoid has awire diameter and number of turns capable of operating from currentproduced by full battery voltage in order to raise said needle valvefrom the closed position to the open position in about 60 μs.
 8. Theswirl injector according to claim 1, wherein the plurality of spiralgrooves comprises six grooves, each groove having a length of about 7.98mm and a cross-sectional area of about 0.23 mm², the swirl injectorbeing adapted for use in a gasoline engine injecting at a pressure ofabout 7.0 MPa.
 9. The swirl injector according to claim 1, wherein theplurality of spiral grooves comprises eight grooves, each groove havinga length of about 5.67 mm and a cross-sectional area of about 0.34 mm²,the swirl injector being adapted for use in a diesel engine injecting ata pressure of about 80.0 MPa.
 10. The swirl injector according to claim1, in combination with a flow meter sensor connected in a vehicle highpressure fuel line, the flow meter sensor comprising: (a) a quartz glassmeasurement tube; (b) a laser diode generating a pair of collimatedlaser beams focused to intersect at a center line of said quartz tube;(c) a PIN diode focused to receive light scattered from the center lineof said quartz tube; (d) an interface board electrically connected tosaid PIN diode for computing instantaneous center line velocity of fuelflowing in said quartz tube; and (e) an engine control module connectedto said interface board and having a microprocessor programmed tocompute instantaneous pressure gradients and volumetric flow rates;whereby said engine control module is capable of precisely regulatingtiming, pulse duration, and pressure of injection in said swirl injectorto adjust the volumetric flow rate to engine load.
 11. A swirl injectorfor a direct injection internal combustion engine comprising: (a) anelongated housing defining a valve body and having a fluid passagedefined axially through the valve body, the housing having a fluid inletplug at a first end adapted for attachment to a pressurized fuel line,and having a nozzle defining a conical valve seat at a second end fordischarging fuel, the nozzle further defining a single cylindricaldischarge orifice descending from the apex of the conical valve seat,the housing further having a shock brake ring disposed transversely inthe fluid passage and defining an upper valve body portion and a lowervalve body portion; (b) a solenoid disposed in the upper valve bodyportion of said housing, the solenoid having a coil encircling the fluidpassage and a polar electrode electrically connected to said coil, thepolar electrode extending through said housing and being adapted forconnection to a triggering circuit for energizing the solenoid forprecise time durations at precisely timed intervals; (c) a needle valvehaving a needle head at a first end and a tip at a second end, theneedle valve having a disk about its circumference, the needle valvebeing disposed in the fluid passage defined in said valve body with thedisk disposed in the lower portion of said valve body and the needlehead extending at least partially inside the coil of said solenoid, theneedle valve having a plurality of helical ridges defining spiralgrooves adjacent the tip, the spiral grooves having a planar bottom walland a pair of planar opposing side walls, the spiral grooves defining anangle of about forty-six degrees with respect to an axis transverse to alongitudinal axis through the needle valve; and (d) a compression springdisposed in the upper portion of said valve body; (e) wherein saidcompression spring biases the needle valve in a closed position in whichthe tip is seated against the conical valve seat defined in said nozzleand wherein a triggering current in said solenoid lifts said needlevalve to an open position in which the tip is raised above the conicalvalve seat in order to discharge fuel from the nozzle; and (f) whereinsaid swirl injector ejects a fuel spray having an umbrella spraysuperimposed on a core jet at a penetration speed, swirl speed, andpitch angle controllable by varying injection pressure for operation ina dual switch mode between early injection and late injection.
 12. Theswirl injector according to claim 11, wherein the tip of said needlevalve is a rounded ball tip.
 13. The swirl injector according to claim11, wherein the spiral grooves have a width-to-depth ratio of 1.5 to 1.14. The swirl injector according to claim 11, wherein the stop disk ofsaid needle valve and said shock brake ring define a lifting gap whensaid needle valve is in the closed position, the lifting gap measuringabout 50 μm.
 15. The swirl injector according to claim 14, wherein saidsolenoid is capable of developing an electromagnetic field of sufficientstrength to raise said needle valve to a closed position in which saidstop disk is seated against said shock brake ring in about 60 μs. 16.The swirl injector according to claim 11, wherein the coil of said soledhas a wire diameter and number of turns capable of operating fromcurrent produced by full battery voltage in order to raise said needlevalve from the closed position to the open position in about 60 μs. 17.The swirl injector according to claim 11, wherein the plurality ofspiral grooves comprises six grooves, each groove having a length ofabout 7.98 mm and a cross-sectional area of about 0.23 mm², the swirlinjector being adapted for use in a gasoline engine injecting at apressure of about 7.0 MPa.
 18. The swirl injector according to claim 11,wherein the plurality of spiral grooves comprises eight grooves, eachgroove having a length of about 5.67 mm and a cross-sectional area ofabout 0.34 mm², the swirl injector being adapted for use in a dieselengine injecting at a pressure of about 80.0 MPa.
 19. The swirl injectoraccording to claim 11, in combination with a flow meter sensor connectedin a vehicle high pressure fuel line, the flow meter sensor comprising:(a) a quartz glass measurement tube; (b) a laser diode generating a pairof collimated laser beams focused to intersect at a center line of saidquartz tube; (c) a PIN diode focused to receive light scattered from thecenter line of said quartz tube; (d) an interface board electricallyconnected to said PIN diode for computing instantaneous center linevelocity of fuel flowing in said quartz tube; and (e) an engine controlmodule connected to said interface board and having a microprocessorprogrammed to compute instantaneous pressure gradients and volumetricflow rates; whereby said engine control module is capable of preciselyregulating timing, pulse duration, and pressure of injection in saidswirl injector to adjust the volumetric flow rate to engine load. 20.The swirl injector according to claim 11, wherein said nozzle ejectsfuel at a pitch angle of about 3° measured between the core jet and alongitudinal axis of said nozzle at low injection pressure and at apitch angle of about 15° measured between the core jet and alongitudinal axis of said nozzle at high injection pressure, whereby theinjector is adapted for dual switching mode between early injection andlate injection.